Capture currency exchange rates

.env_template

@@ -13,3 +13,4 @@ TWILIO_SID=
 TWILIO_TOKEN=
 TWILIO_MESSAGING_SERVICE=
 MAPBOX_TOKEN=
+OPEN_EXCHANGE_RATES_API_ID=

commcare_connect/accounting/apps.py

@@ -0,0 +1,6 @@
+from django.apps import AppConfig
+
+
+class AccountingConfig(AppConfig):
+    default_auto_field = "django.db.models.BigAutoField"
+    name = "commcare_connect.accounting"

commcare_connect/accounting/migrations/0001_initial.py

@@ -0,0 +1,46 @@
+# Generated by Django 4.2.5 on 2024-09-12 16:16
+
+from decimal import Decimal
+from django.db import migrations, models
+
+
+def create_task(apps, schema_editor):
+    schedule, _ = CrontabSchedule.objects.get_or_create(
+        minute="00",
+        hour="23",
+        day_of_week="*",
+        day_of_month="*",
+        month_of_year="*",
+    )
+    PeriodicTask.objects.update_or_create(
+        crontab=schedule,
+        name="update_exchange_rates",
+        task="commcare_connect.accounting.tasks.update_exchange_rates",
+    )
+
+
+def delete_task(apps, schema_editor):
+    PeriodicTask.objects.get(
+        name="update_exchange_rates",
+        task="commcare_connect.accounting.tasks.update_exchange_rates",
+    ).delete()
+
+class Migration(migrations.Migration):
+    initial = True
+
+    dependencies = []
+
+    operations = [
+        migrations.CreateModel(
+            name="Currency",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("code", models.CharField(max_length=3, unique=True)),
+                ("name", models.CharField(db_index=True, max_length=25)),
+                ("symbol", models.CharField(max_length=10)),
+                ("rate_to_default", models.DecimalField(decimal_places=9, default=Decimal("1.0"), max_digits=20)),
+                ("date_updated", models.DateField(auto_now=True)),
+            ],
+        ),
+        migrations.RunPython(create_task, delete_task)
+    ]

commcare_connect/accounting/models.py

@@ -0,0 +1,37 @@
+from decimal import Decimal
+
+from django.db import models
+
+from commcare_connect.cache import quickcache
+
+DEFAULT_CURRENCY = "USD"
+
+
+class Currency(models.Model):
+    """
+    Keeps track of the current conversion rates so that we don't have to poll the free, but rate limited API
+    from Open Exchange Rates.
+    """
+
+    code = models.CharField(max_length=3, unique=True)
+    name = models.CharField(max_length=25, db_index=True)
+    symbol = models.CharField(max_length=10)
+    rate_to_default = models.DecimalField(
+        default=Decimal("1.0"),
+        max_digits=20,
+        decimal_places=9,
+    )
+    date_updated = models.DateField(auto_now=True)
+
+    class Meta:
+        app_label = "accounting"
+
+    @classmethod
+    def get_default(cls):
+        default, _ = cls.objects.get_or_create(code=DEFAULT_CURRENCY)
+        return default
+
+    @classmethod
+    @quickcache(["code"], timeout=60 * 60)
+    def by_code(cls, code):
+        return cls.objects.get(code=code)

commcare_connect/accounting/tasks.py

@@ -0,0 +1,35 @@
+import json
+import logging
+import urllib
+
+from django.conf import settings
+
+from config import celery_app
+
+from .models import Currency
+
+logger = logging.getLogger(__name__)
+
+
+@celery_app.task()
+def update_exchange_rates():
+    app_id = settings.OPEN_EXCHANGE_RATES_API_ID
+    if app_id:
+        try:
+            logger.info("Updating exchange rates...")
+            rates = json.load(
+                urllib.request.urlopen("https://openexchangerates.org/api/latest.json?app_id=%s" % app_id)
+            )["rates"]
+            default_rate = float(rates[Currency.get_default().code])
+            for code, rate in rates.items():
+                currency, _ = Currency.objects.get_or_create(code=code)
+                currency.rate_to_default = float(rate) / default_rate
+                currency.save()
+                logger.info(
+                    "Exchange rate for {code} updated {rate:f}.".format(
+                        code=currency.code,
+                        rate=currency.rate_to_default,
+                    )
+                )
+        except Exception as e:
+            logger.error("Error updating exchange rates: %s" % str(e))

config/settings/base.py

@@ -68,6 +68,7 @@
 ]
 
 LOCAL_APPS = [
+    "commcare_connect.accounting",
     "commcare_connect.commcarehq_provider",
     "commcare_connect.form_receiver",
     "commcare_connect.opportunity",
@@ -339,3 +340,5 @@
 TWILIO_AUTH_TOKEN = env("TWILIO_TOKEN", default=None)
 TWILIO_MESSAGING_SERVICE = env("TWILIO_MESSAGING_SERVICE", default=None)
 MAPBOX_TOKEN = env("MAPBOX_TOKEN", default=None)
+
+OPEN_EXCHANGE_RATES_API_ID = env("OPEN_EXCHANGE_RATES_API_ID", default=None)